Influence of morphine microinjected into head of caudate nucleus on electric activities of nociceptive neurons in parafascicular nucleus of rat thalamus.
Morphine (8 micrograms/microliter) was injected into the head of the caudate nucleus (CN). The pain-discharges of the pain-excitation neurons (PEN) in the parafascicular nucleus (Pf) were inhibited, ie, decreasing in frequency of pain-discharges and lengthening in latent period of pain-discharges. The inhibitory effect of the pain-inhibition neurons (PIN) in the Pf induced by noxious peripheral stimulation were relieved, ie, increasing the firing rate and shortening the inhibitory duration. The opiate receptor antagonist naloxone (0.75 mg/kg, ip) blocked the above effects of morphine. These results suggest that the intracaudate opioid peptide system play an important role in the modulation of pain information in the Pf of thalamus.
Li
B Y
BY
Department of Physiology, Harbin Medical University, China.
Xu
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D000818:Animals; D002421:Caudate Nucleus / Q000502:physiology*; D004594:Electrophysiology; D008297:Male; D008845:Microinjections; D009020:Morphine / Q000494:pharmacology*; D009474:Neurons / Q000502:physiology; D009619:Nociceptors / Q000502:physiology*; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D013787:Thalamic Nuclei / Q000502:physiology*
D009020:Morphine